1. Field of the Invention
This invention relates to a step-by-step motor able to carry out up-and-down motion, and particularly to one provided with a bayonet socket having electric wires respectively connected with a right-handed coil and a reverse coil. After the electric wires are electrically connected, the right-handed coil or the reverse coil will be electrified to actuate a magnet and a connecting member to rotate clockwise or counterclockwise. The present invention drives drive a top rod to move up or down linearly, and is able to carry out transmission steadily and effectively, small in size and occupies less space.
2. Description of the Prior Art
Generally, the headlamp of an automobile is installed with a step-by-step motor for adjusting the radiating height of the headlamp. A conventional step-by-step motor, as shown in FIGS. 1 and 2, includes a threaded rod 11 threadably combined with the threaded hole 121 of a shaft bushing 12. The shaft bushing 12 has one end extending outward and forming a polygonal bulging block 122 to be engaged with the engage hole 131 of a gear disk 13. An adjusting rod 14 intersecting at right angles with the threaded rod 11 has its lower end engaged with a gear 15 that is engaged with the gear disk 13. Then, all the members mentioned above are disposed in the interior of a fixing base 16 and a positioning base 17, and the adjusting rod 14 and the threaded rod 11 have their outer ends respectively extending out of the fixing base 16 and the positioning base 17. When the adjusting rod 14 is turned around, the threaded rod 11 will be driven to shift by interaction of the gear 15, the gear disk 13 and the shaft bushing 12. However, the conventional step-by-step motor has to be additionally provided with a transmission device at the exterior of the adjusting rod 14 for driving the adjusting rod 14 to rotate, thus enlarging the whole dimensions, taking too much space and failing to control operation precisely.